The present invention relates to a slip-controlled brake system for automotive vehicles comprising one static brake circuit into which pressure fluid out of a dynamic pressure fluid circuit can be introduced when a control action becomes necessary. The system further includes one dynamic brake circuit with a master cylinder assembly and a hydraulic booster with a hydraulic auxiliary-pressure supply system. Wheel sensors and electronic circuits are provided for determining the wheel rotational behavior and for generating electric braking-pressure control signals which serve to control pressure-fluid inlet valves and outlet valves inserted into the pressure fluid lines for the purpose of slip control.
In vehicles with a high total weight, very great boosting forces are necessary for obtaining a comfortable pedal feeling. The dimensioning of the boosting forces is, however, subject to legislated prescriptions so that compromises with respect to a longer pedal travel must be accepted. That is, if safe braking which can be easily governed by the driver is desired upon booster failure.
It is an object of the present invention to devise a brake system of the type described which, even on failure of the hydraulic auxiliary-pressure supply system, enables safe braking with comparatively low pedal forces and a very small lost pedal travel.